birefringence

Definition of birefringence

1: the refraction of light in an anisotropic material (such as calcite) in two slightly different directions to form two rays
According to G. Blom of Philips, video disc acrylics must be optically clear and free of striations and birefringence. Clear vinyl often is highly birefringent. — Technical Survey

—called alsodouble refraction

2: the visual effect produced by birefringence
The diagnosis was made before scanning in 22 patients by the detection of deposits with apple-green birefringence …— Philip N. Hawkins et al.

3: the difference between the angles of refraction of light rays exhibiting birefringence

The first known use of birefringence was
in 1879

Medical Definition of birefringence

: the refraction of light in an anisotropic material in two slightly different directions to form two raysalso: the visual effect produced by birefringence The diagnosis was made before scanning in 22 patients by the detection of deposits with apple-green birefringence … — Philip N. Hawkins et al., The New England Journal of Medicine, 23 Aug. 1990